關島

Modern capacitive touch input and proximity sensing technologies are rigid and limited to flat substrates making it impossible to apply them onto objects with irregular geometries like textiles or car handles. Furthermore, the high cost restricts the applications to small surfaces and cannot be scaled up to be applied on large surfaces such as walls. Therefore, a paint-on scheme would broaden the applications of capacitive touch input and proximity sensing devices. Paintable capacitive sensors are an emerging technology hindered by the high cost and lackluster properties of conductive paints. Existing conductive paints utilize expensive filler materials such as silver and gold to achieve high conductivity but suffer from low surface area. High surface area is critical for capacitive proximity sensors to detect objects from far distances and for overall sensitivity. Carbonaceous alternatives using micronized graphite exhibit low conductivity, require high loadings and most disintegrate when in contact with water. Multilayer graphene nanoplatelets are investigated for their high conductivity, high surface area, low cost, flexibility and eco friendliness. A waterproof acrylic latex is combined with multilayer graphene and dispersed via bath sonication. The optimal time of sonication and optimal graphene loading is determined through systematic testing. An Arduino Uno is loaded with a CapSense library and the graphene based paint is utilized as the interface to sense both touch and proximity.

Current research shows Northern Guam to be composed of porous limestone bedrock which allow groundwater to flow out. One large discharge point has already been identified last year in north-western Guam at Ayuyu Cave. However, little is known about Tumon Bay which is known to comprise karst watersheds which should allow for SGD. This project has examined invisible groundwater discharge using a salinity meter and was able to detect two areas of concentrated freshwater discharges in Tumon Bay, with a few minor ones scattered throughout the bay. These seeps were found to have consistently lower salinity while pH varied, and hosted more marine life than other high salinity areas. Further unique coral growth in Tumon Bay’s inner lagoon was associated with these two freshwater discharges with the pH levels further segregating the types of coral species found during on-site observation. Two coral communities, staghorn Acropora and massive Porites, were found adjacent to the surveyed groundwater seeps. It’s inferred that lower wave energy in eastern Tumon Bay allows for greater plankton and other microbial growth leading to more heterotrophic coral growth, favoring Porites corals, while Western Tumon Bay has higher wave energy which leads to the growth of more autotrophic corals, such as the Acropora found in the first area surveyed. This is the first study to document the presence, location, and consequences of invisible freshwater discharges across the billion-dollar bay. This study gauges the effects of SGD on inner shore habitats, also providing a coral cover assessment across Tumon Bay using transects and quadrats. These discoveries allow for strategic coral planting, designated areas needing government protection, and show areas of appealing inner lagoon coral growth for tourism.